Plastic substrate and device including the same

A plastic substrate, comprising:

• a plastic film;
• a reflective metal layer formed on the plastic film, wherein the reflective metal layer has a thickness ranging from 1 to 1000 nm;
• a resin layer formed on the reflective metal layer, wherein the resin layer has a thickness ranging from 10 nm to 25.5 μm,
• wherein the plastic film and the resin layer are made of polyimides,
• wherein the polyimides have an average coefficient of linear thermal expansion of 50.0 ppm/° C. or less when measured in a temperature range from 50° C. to 250° C. using a thermomechanical analyzer for a film thickness of 50-100 μm, with a yellowness index of 15 or less,
• wherein the reflective metal layer has a multilayered structure,
• wherein the reflective metal layer comprises a lower metal layer and an upper metal layer,
• wherein the lower metal layer is made of at least one metal selected from the group consisting of aluminum, magnesium and alloys thereof;
• and
• wherein the upper metal layer is made of ITO (indium tin oxide) or IZO (indium zinc oxide), and
• wherein the plastic substrate has a light transmittance of 50% or more at a wavelength of 500 nm and a surface resistivity of 2.5×106Ω/sq or less.